1. Field of the Invention
This invention relates generally to a tone arm assembly, and is directed more particularly to a tone arm assembly which is controlled and positioned by electro-magnetic forces.
2. Description of the Prior Art
It is the customary practice in record players to derive the power for moving the tone arm from the driving motor for the turntable by means of an intermediate cam disc driven by the shaft of the turntable. However, this is not an ideal solution, since the rotational speed of the turntable is inevitably affected by such arrangement which also adversely affects the sound reproducing system if manual controls are located on the resiliently supported chassis of the record player.
A record player to overcome the above-described defects of the conventional record player is disclosed in the U.S. Pat. No. 3,993,315 in which separate driving means are provided for moving the tone arm both horizontally and vertically and are controlled by switch means actuated in response to selection and/or detection of the appropriate conditions for respective movements of the tone arm. In such record player, the tone arm movements may be controlled entirely independent of the turntable, for example, for raising the tone arm in response to completion of the playing of a record. However, in the record player disclosed in U.S. Pat. No. 3,993,315, the tone arm is moved in the horizontal direction by means of a mechanical gear arrangement. A feed pitch of the gear arrangement may not coincide with the groove pitch of the record disc. Accordingly, the horizontal movement of the tone arm is not always smooth and satisfactory.
Another record player is known, for example, as disclosed in U.S. Pat. Nos. 4,023,130 and 3,830,505, in which the tone arm is driven in the vertical direction in respect to the record disc by means of electro-magnetic force. However, there is no suggestion to drive the tone arm in the horizontal direction with respect to the record disc by the use of electromagnetic force.
In some conventional record players, the tone arm is mechanically braked so as to stabilize movements in the lead-in direction and the lead-out direction. However, these record players are disadvantageous in that they are complex in construction, expensive and susceptible to trouble.
Further, in some existing record players, the direction of movement of the tone arm is automatically charged-over from the lead-in direction to the lead-out direction in response to a mechanical detection or microswitch detection, and, upon actuation of a start switch, the tone arm is automatically led-in from a rest position on an arm rest to a set-down position on the record disc. However, these record players are complex in construction and the required parts are expensive. Further, if the start switch is actuated at a time when the tone arm is not correctly positioned on the arm rest, the tone arm is driven in the lead-in direction only after a substantial delay leading the operator to wonder if the record player might be out of order.
A tone arm assembly provided with horizontal and vertical drive means for the tone arm is disclosed in the copending U.S. Pat. application Ser. No. 790,047, filed Apr. 22, 1977, and having a common assignee herewith.